relative clause

[amitesh.podder]

Please help to make my conception clear on the use of relative clause.

1. Sulphar is one of the substances that burns when it comes in contact with air
or
Sulphar is one of the substances that burn when they come in contact with air

2. The Painting of Da-Vinci, which is damaged, has raised $3m on the first day of the Auction.

Is the above construction right meaning wise i.e. whether "which" is properly referring to the Painting or not?

[pdarun]

My opinion, second option for 1 is right since that refers to substances and not sulphur. Hence the verb must be plural - hence that burn is right

For the Da Vinci painting, I think the sentense is wrong because of the tense which is damaged. The simple present tense in is means something was not true in the past, but is true today - a change that is current. The current answer should be

The Painting of Da-Vinci, which was damaged, has raised $3m on the first day of the Auction.